Flexible width Theme with wider maximum

My site was developed with Twenty Ten. Desiring a wider (than 1,000 pixels?) display, I tried both Coraline and Twenty Eleven thinking flexible width would do the trick. No - the maximum width in both is the same as the fixed width in Twenty Ten. Are there any flexible width themes (Premium or Free) that offer a wider maximum?

I should mention that with the custom design upgrade you can change the maximum width to anything you want through the CSS, but the header image quality issue will then become very apparent and you will likely not be happy with it.